University of Twente Student Theses
Wave orbital motion on the Dutch lower shoreface : observations, parameterizations and effects on bed-load sediment transport
Treurniet, B.A. (2018) Wave orbital motion on the Dutch lower shoreface : observations, parameterizations and effects on bed-load sediment transport.
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| Abstract: | As part of the Coastal Genesis 2.0 campaign, orbital wave velocities are measured with Acoustic Doppler Velocimeters at two different locations on the lower shoreface near the Amelander Zeegat, at -16m and -20m NAP. Using the Van Rijn (2007) sediment transport formulations, year-round weighted averaged bed-load sediment transports due to wave orbital motion of 11,5 m3/y/m and 3,2 m3/y/m are found for -16m and -20m NAP respectively in a direction almost in line with the wave direction. Parameterizations by Isobe & Horikawa (1982) and Ruessink et al. (2012) predict a near-bed wave velocity profile as a function of surface wave characteristics. The velocity profile is compared with the orbital wave velocities, measured with the ADV’s. The Isobe&Horikawa parameterization shows more skewed waves than the Ruessink parameterization, but lower significant orbital velocities. Orbital wave velocities have a larger influence on bed-load sediment transport than skewness. Bed-load sediment transports calculated with the Isobe & Horikawa parameterization approximates the bed-load sediment transport rates, calculated from measured orbital velocities best. The found sediment transport rates at -20m could be used to make an estimation about net-sediment transport into the coastal foundation. The -20m NAP contour is the seaward border of the coastal foundation, which must be maintained by sand nourishments. In the 3rd Coastal Memorandum (3e Kustnota) is decided that yearly 12Mm3 sand should be nourished to the coastal foundation, assuming negligible sediment transport takes place over the -20m NAP contour. The found bed-load sediment transport rate at -20m NAP of 3,5 m3/y/m comes down to nearly 1 Mm3 per year. Extrapolated to the entire Dutch shoreline, this is a considerable amount. |
| Item Type: | Essay (Bachelor) |
| Faculty: | ET: Engineering Technology |
| Subject: | 56 civil engineering |
| Programme: | Civil Engineering BSc (56952) |
| Link to this item: | https://purl.utwente.nl/essays/77210 |
| Export this item as: | BibTeX EndNote HTML Citation Reference Manager |
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